Effective thermally imageable compositions suitable for use as imageable coatings on masks and on precursors for printed circuit and other electronic parts are described in WO99/08879. However there are some situations where these compositions are not optimal. For example they may not be sufficiently physically robust for some applications, particularly when coated on both sides of a thin, flexible substrate. Although there are available other compositions which are more physically robust, these generally require more imaging energy for a given dissolution rate in a given developer.
Accordingly, there remains a need for technological advances in relation to thermally imageable articles for use in mask and electronic part manufacture; and in particular there remains a need for articles which have a coating which is both physically robust and have good image forming characteristics.
The types of electronic parts whose manufacture may use an imageable coating include printed wiring boards (PWBs), thick- and thin-film circuits, comprising passive elements such as resistors, capacitors and inductors; multichip devices (MDCs); integrated circuits (ICs); and active semiconductor devices. The electronic parts may suitably comprise conductors, for example copper board; semiconductors, for example silicon or germanium; and insulators, for example silica as a surface layer with silicon beneath, with the silica being selectively etched away to expose portions of the silicon beneath (a step in the manufacture of e.g. field effect transistors). In relation to masks, a required pattern may be formed in the coating on the mask precursor, which is then used as a mask in a later processing step, in forming a pattern on, for example, a printing or electronic part substrate.